Defrosting system for refrigerating apparatus



Nov. 21, 1950 O. J.-NUSSBAUM 2,530,440

a DE'FROSTING SYSTEM FOR REFRIGERATING APPARATUS Filed July 26; 194'! INVENTOR jbAT'roRNEYs Patented Nov. 21, 1950 UNITED STATES PATENT orrlcs I DEFROSTING SYSTEM FOR REFBIGERAT- ING APPARATUS Otto J. Nussbaum, Trenton, N. J., assignor to' Kramer Trenton Company, Trenton, N. 1., a corporation of New Jersey Application July 26, 1947, Serial No. 783,982

13 Claims.

This inventionrelates to refrigerating apparatus and, more particularly, to improved means for defrosting the evaporator within the refrigeration chamber.

An object of the invention is to provide an arrangement or system in which hot gas supplied from the compressor serves periodically to defrost the evaporator within the refrigeration chamber while a second evaporator, located without the said chamber and coupled with a pressure reducing means, such as an expansion valve, serves to revaporize the liquid flowing from the evaporator within the refrigeration chamber as a result of defrosting so that the said liquid reaches the inlet of the compressor in the form of gas.

Another object is to provide such an arrangement or system in which the defrosting step is efliciently and eiiectively accomplished even though the installation is one in which the compressor and condenser are located so as to be exposed to weather conditions and in spite of low ambient temperatures.

Another object is to provide such an arrangement or system in which conduits interconnecting the two evaporators and the compressor are provided with means for causing the fluid flowing from the evaporator located within the refrigeration chamber to the compressor to travel either directly to the compressor or through the other evaporator with its expansion valve before reaching the compressor.

Another object is to provide such an arrangement or system in which a hot gas line connects the outlet of the compressor with the inlet of the evaporator located in the refrigeration chamber, and in which valves are located in the said hot gas line and in the conduit running from said evaporator to the compressor, means being provided for periodically opening the one valve and closing the other and vice versa.

Another object is to provide such an arrangement or system in which each evaporator may be provided with a fan, and in which there is means for causing the fan connected with the evaporator located within the refrigeration chamber to be activated when the other fan is not activated and vice versa.

Another object is to provide such an arrangement or system in which, during normal operation, the evaporator located without the refrigeration chamber is by-passed by the fluid flowing from the evaporator within the said chamber to the compressor, and in which, during defrosting periods, the fluid flowing from the evaporator mal operation and defrosting operation and like wise controls the activation and deactivation of the several elements during each of said periods.

A further object consists in providing certain improvements in the form, construction, arrangement, and location of the several parts whereby the above named and other objects inherent in the structure may be effectively attained.

In connection with the installation of refrigerating apparatus it is sometimes desirable, in view of building structure or arrangement, to locate the compressor unit, which commonly includes the condenser, out of doors which practice is feasible when the condenser is of the air-cooled type. However, at geographical points where the temperature is normally low or where winters are severe difficulty is often encountered, particularly in those systems employing hot gas defrosting, due to an insufficient supply of heat for the defrosting step. This difficulty is exaggerated when the water vapor load from substances in the refrigerating chamber is high while the temperature surrounding the compressor and condenser is low, because this condition causes ice to form rapidly on the evaporator in the refrigeration chamber while the low ambient temperature at the compressor and condenser unit reduces the supply of heat requisite for satisfactory defrosting. The present invention is calculated to overcome the difllculty just described and to impart additional advantages to the performance of the apparatus or system.

A practical embodiment of the invention is diagrammatically represented in the accompanying drawing, in which a compressor is denoted by i and is connected by pipe 2 with a condenser 3 which is, in turn, connected by pipe 4 with a receiver 5. These parts just mentioned may be of any well known or approved form and arrangement and they will not be further described as those skilled in this art are thoroughly familiar with them and their particular construction and arrangement constitute no part of the present invention. The receiver is connected by the usual supply pipe line 6 with a pressure reducing device, such as an expansion valve I, which may be of any well known or approved form and itself connected by pipe 8 with an evaporator 9, of any approved or desired construction, which is mounted or hung by suitable means (not shown) within the refrigeration chamber of which two walls are shown and marked Ill, II. The usual fan l2, and its motor l3, are mounted adjacent the evaporator to circulate the chilled air throughout the refrigeration chamber.

From the outlet of the evaporator 9 a suction pipe or conduit It leads to the intake port of the compressor I; and a branch pipe or conduit l5 leads from pipe It to the inlet of a second evaporator H; which is mounted or hung by any appropriate means at a point without the refrigeration chamber III, II. The outlet of evaporator I6 is connected by another pipe or conduit H with the suction pipe I 4 at a point adjacent the compressor. It will be observed that the arrangement just described provides two paths or courses for the fluid traveling from the evaporator 9 that is within the refrigeration chamber to the compressor; one of the paths or courses being direct to the compressor and the other traversing the evaporator l6 that is positioned without the refrigeration chamber. A solenoid valve 18 is located in the suction pipe I at a position intermediate the compressor I and the point at which conduit l5 connects with pipe Hi; and it will be clear that, when valve I8 is open, fluid from evaporator 9 may travel through pipe M directly to compressor I while, when valve I8 is closed, the said fluid must pass through pipe l5, evaporator I6 and pipe Il' to reach the compressor.

In the pipe or conduit I5 there is placed a pressure reducing means, such as an expansion valve l9, which may be of any well known or approved form, the function of the said valve l9 being to expand and reduce the pressure of the liquid flowing from evaporator 9 during periods in which the said evaporator is being defrosted. In other words, expansion valve l9 functions with respect to evaporator IS in a manner similar to that in which expansion valve 1 functions with respect to evaporator 9.

A feeler tube 20, of any well known or approved form, is associated with suction pipe 14 at a point adjacent evaporator 9 and is connected by a small diameter pipe 2| with expansion valve 1 in order to regulate the action of the latter in a manner well understood by those skilled in this industry; and the refrigerant feed pipe 6 and suction pipe l4 both pass through a heat exchanger 22, which may be of well known or approved construction, for the purpose of regulating the temperature of the refrigerant fed to valve 1 as well as the relative temperature of the liquid refrigerant flowing into the evaporator 9 and the vaporized refrigerant outflowing therefrom, all of which is also well known and familiar practice in this industry.

The discharge of compressor l is connected by a pipe or conduit 23 with the evaporator 9 for the purpose of periodically supplying hot gas to defrost the latter, and a second solenoid valve 24 is located in pipe 23 for the automatic closing and opening thereof. A hand valve 25 is positioned in pipe 23 at a point intermediate compressor l and valve 24 for the purpose of manually shutting oil the defrosting line during 0ccasional servicing of the system. The evapora- -tor l6 located without the refrigeration chamber I0, II, is, like the evaporator 9, equipped with the usual fan 26 and fan motor 21 for the purpose of increasing its radiation and vaporizing effect, although this fan 26 and its motor may be omitted, if desired.

An electric timer, preferably of the self-starting type, various forms of which are well known and on the market, is indicated by 28 and is connected by wires 29, 39, with any suitable source of electric current, such, for instance, as a commercial supply line. This timer serves to control the solenoid valves I8 and 24 as well as the fan motors l3 and 21, the timer being in electric circuit with valve I3 through wires 3|, 32; with valve 24 through wires 33, 34; with fan motor l3 through wires 35, 36; and with fan motor 21 through wires 31, 38. The timer 28 may be set by the installing engineer to initiate defrosting periods at predetermined intervals selected by him and to continue each defrosting operation for a predetermined duration also selected by him; the apparatus just described being so arranged that, when the timer initiates a defrosting period it actuates solenoid valve I8, which is normally open, so as to close the valve; and it actuates solenoid valve 24, which is normally closed, so as to open the valve. Simultaneously, the timer 28 interrupts the current flow to fan motor l3 which causes fan l2 that is normally operating to cease rotating; and completes the current circuit to fan motor 21 which causes fan 26, that is normally idle, to start rotating. At the end of the defrosting operation, timer 28 reverses its effects upon the parts just mentioned, thereby opening valve l8, closing valve 24, starting fan l2, and stopping fan 26.

It will be understood that the evaporator 9 is provided with the usual drip pan (not shown) which is defrosted with the evaporator, and a suitable pipe 39 serves to drain off the water resulting from defrosting to the sewer or anyother suitable disposal provision.

In operation, valve 24 is normally closed while valve 25 is normally open, and the hot gas from the compressor l passes through pipe 2, condenser 3, pipe 4, receiver 5, pipe 6, expansion valve 1, and pipe 8 to evaporator 9 for the purpose of chilling the refrigeration chamber Ill, ll, all as i usual, customary and well understood. As valve I8 is normally open, the refrigerant fluid passing out of evaporator 9 flows through suction pipe [4 and back to the intake of compressor I, thus completing the cycle of fluid travel which continues during normal refrigerating operations.

The self-starting electric timer 28 has previously been set by the engineer to initiate at predetermined periods defrosting steps continuing for predetermined durations. When, now, a time for defrosting evaporator 9 arises, the said timer functions to close valve' l8, open valve 24, stop fan 12 and start fan 28. With this setup the hot gas from the compressor flows through pipe 23 to evaporator 9 and rheltstlie ice with which the latter and its drip pan are encrusted, the water resulting therefrom passing off through pipe 39. The hot gas in performing its defrosting function is in turn chilled by the ice on the evaporator 9 and drip pan so that, when it emerges from the said evaporator, it flows through pipe [4 as a liquid. Valve l8 being closed compels this liquid to pass through pipe l5 and expansion valve H, to and through evaporator l5 and thence through pipe llto the intake of compressor l. The effect of the expansion valve I9 is to reduce the pressure of the liquid and the effect of the evaporator IS, with its fan 26,

is to revaporize or reevaporate the liquid so that it passes to the compressor as a gas, thereby avoiding the slugging of liquid through the compressor intake which would seriously handicap the operation of the apparatus and reduce its capacity to supply heat for defrosting. When the predetermined duration of the defrosting period has expired, the timer 28 again functions to close valve 24, open valve [8, start fan l2 and stop fan 26. Whereupon the apparatus resumes its operation as a refrigerating system at full efficiency because of the defrosting of the refrigerating chamber evaporator 9 and its drip pan.

If desired, a pressure switch .40, of any well known or approved form, may be connected with pipe I 4 at a point intermediate the evaporator 9 and the junction of pipes 14 and [5, for the usual purpose Of starting and stopping the compressor motor (not shown) in response to the pressure existing in pipe H. The switch 40 is connected to the compressor motor by wires 4|, 42, in any customary manner, the same being so well understood in this industry as to call for no illustration or description.

From the foregoing it will be seen that, during normal operation, evaporator 9 acts as an evaporator and condenser 3 is performing its usual function of condensing the hot gas received from the compressor; while, during the defrosting periods, evaporator 9 acts as a condenser, evaporator I6 acts as an evaporator and condenser 3 is practically inactive.

The functioning of evaporator l6, especially in conjunction with its expansion valve I9, is such that the liquid returning from evaporator 9 is thoroughly vaporized even though evaporator I6 is located out of doors and subject to very low temperatures. This greatly assists the functioning of compressor I and condenser 3 and causes adequate heat to be provided for each defrosting of evaporator 9, even though the compressor and condenser may likewise be located out of doors and exposed to low ambient temperatures. Another operational advantage resides in the fact that this structure and arrangement eliminates objectionably heavy loads upon the compressor motor either during defrosting periods or immediately after the resumption of normal operations. Again, the evaporator l6 may be of considerably less heat transfer surface than evaporator 9 and yet serve its purpose adequately and satisfactorily. Finally, the apparatus, arrangement or system is comparatively simple, may be composed of standard parts, adapts itself to many different installation requirements, and will function with complete satisfaction regardless of climatic conditions. All the objects hereinabove mentioned are attained to a full degree, and the user also receives the advantage of numerous other desirable features inherent in the construction and arrangement.

While the utility of this invention has been emphasized under conditions in which the compressor, condenser and evaporator are subject to low ambient temperatures, it should be noted that it is also well adapted to situations in which the said parts are subject to moderate or warm temperatures, and the pressure reducing device l9 may even be omitted if the surrounding temperature is fairly high, e. g., 60 F. or higher.

When, in the claims, I use the expression a refrigeration chamber, I intend to include, not only a normally closed chamber, but also other forms of refrigeration spaces, compartments or sections even though they normally be partly open, such, for instance, as the refrigeration spaces in self-service display cases.

It will be understood that various changes may be resorted to in the form, construction, arrangement and material of the several parts without departing from the spirit and scope of the invention; and hence I do not intend to be limited to details herein shown or described, except as they may be included in the claims or required by disclosures of the prior art.

What I claim is:

1. Apparatus of the character described comprising, a compressor, a condenser, a refrigeration chamber, an evaporator located within said chamber, a second evaporator located without said chamber, conduits interconnecting the two evaporators and the compressor, pressure reducing means in the conduit which connects the two evaporators, means for controlling said conduits to permit fluid to flow from the outlet of said first evaporator either directly to the inlet of the compressor or by a course passing through the pressure reducing means and said second evaporator, and a hot gas line connecting the outlet of the compressor with the inlet of said first evaporator without passing through the condenser.

2. Apparatus of the character described comprising, a compressor, a condenser, a refrigeration chamber, an evaporator located within said chamber, a second evaporator located without said chamber, conduits interconnecting the two evaporators and the compressor, pressure reducing means in the conduit which connects the two evaporators, said conducts being arranged so as to permit fluid to flow from the outlet of said first evaporator either directly to the inlet of the compressor or by a course passing through the pressure reducing means and said second evaporator, a hot gas line connecting the outlet of the compressor with the inlet of said first evaporator without passing through the condenser, and automatic means for closing the conduit leading directly from the outlet of said first evaporator to the inlet of the compressor and opening said hot gas line.

3. Apparatus of the character described comprising, a compressor, a condenser, a refrigeration chamber, an evaporator located within said chamber, a second evaporator located without said chamber, conduits interconnecting the two evaporators and the compressor, pressure reducing means in the conduit which connects the two evaporators, said conduits being arranged so as to permit fluid to flow from the outlet of said first evaporator either directly to the inlet of the compressor or by a course passing through the pressure reducing means and said second evaporator, a hot gas line connecting the outlet of the compressor with the inlet of said first evaporator without passing through the condenser, and automatic means for simultaneously closing the conduit leading directly from the outlet of said first evaporator to the inlet of the compressor and opening said hot gas line.

4. Apparatus of the character described comprising, a compressor, a refrigeration chamber, an evaporator located within said chamber, a second evaporator located without said chamber, conduits interconnecting the two evaporators and the compressor, pressure reducing means in the conduit which connects the two evaporators, said conduits being arranged so as to permit fluid to flow from the outlet of said first evaporator either directly to the inlet of the compressor or by a course passing through the pressure reducing means and said second evaporator, a hot gas line connecting the outlet of the compressor with the inlet of said first evaporator, automatic means for simultaneously closing the conduit leading directly from the outlet of said first evaporator to the inlet 01 the compressor and opening said hot gas line, a fan associated with each of said evaporators, means for driving said fans, and automatic means for stopping the fan associated with said first evaporator and starting the fan associated with said second evaporator when the conduit leading directly from the outlet of said first evaporator to the inlet of the compressor is closed.

5. Apparatus of the character described comprising, a compressor, a condenser, a refrigeration chamber, an evaporator located within said chamber, a second evaporator located without said chamber, a conduit connecting the outlet of said first evaporator with the inlet of the compressor, a second conduit connecting said first conduit with the inlet of said second evaporator, a third conduit connecting the outlet of said second evaporator with the inlet of the compressor, a valve in said first conduit for closing it and causing the fiuid from the said first evaporator to pass through said second conduit, second evaporator and third conduit, and a hot gas line connecting the outlet of the compressor with the inlet of the said first evaporator without passing through the condenser.

6. Apparatus oi the character described comprising, a compressor, a condenser, a refrigeration chamber, an evaporator located within said chamber, a second evaporator located without said chamber, a conduit connecting the outlet 'said first evaporator with the inlet of the compressor, a second conduit connecting said first conduit with the inlet of said second evaporator, a third conduit connecting the outlet of said second evaporator with the inlet of the compressor, pressure reducing means in said second conduit, a valve in said first conduit for closing it and causing the fluid from the said first evaporator to pass through said second conduit,

pressure reducing means, second evaporator and third conduit, and a hot gas line connecting the outlet of the compressor with the inlet of the said first evaporator without passing through the condenser.

7. Apparatus of the character described comprising, a compressor, a condenser, a refrigeration chamber, an evaporator located within said chamber, a second evaporator located without said chamber, a conduit connecting the outlet of said first evaporator with the inlet of the compressor, a second conduit connecting said first conduit with the inlet of said second evaporator, a third conduit connecting the outlet of said second evaporator with the inlet of the compressor, pressure reducing means in said second conduit, a valve in said first conduit for closing it and causing the fluid from the said first evaporator to pass through said second conduit, pressure reducing means, second evaporator and third conduit, a hot gas line connecting the outlet of the compressor with the inlet of said first evaporator without passing through the condenser, a second valve in said hot gas line, and means for periodically closing said first valve and opening said second valve and for opening said first valve and closing said second valve.

8. Apparatus oi the character described comprising, a compressor, a condenser, a refrigeration chamber, an evaporator located within said chamber, a second evaporator located without said chamber, a conduit connecting the outlet of said first evaporator with the inlet of the compressor, a second conduit connecting said first conduit with the inlet of said second evaporator, a third conduit connecting the outlet 0! said second evaporator with the inlet or the compressor, pressure reducing means in said second conduit, an automatic valve in said first conduit for closing it and causing the fluid from the said.

first evaporator to pass through said second conduit, pressure reducing means, second evaporator and third conduit, and a hot gas line connecting the outlet of the compressor with the inlet of said first evaporator without passing through the condenser.

9. Apparatus of the character described comprising, a compressor, a condenser, a refrigeration chamber, an evaporator located within said chamber, a second evaporator located without said chamber, a conduit connecting the outlet of said first evaporator with the inlet of the compressor, a second conduit connecting said first conduit with the inlet of said second evaporator, a third conduit connecting the outlet of said second evaporator with the inlet of the compressor, pressure reducing means in said second conduit, a valve in said first conduit for closing it and causing the fiuid from the said first evaporator to pass through said second conduit,

.pressure reducing means, second evaporator and third conduit, a hot gas line connecting the outlet of the compressor with the inlet of said first evaporator without passing through the condenser, a second valve in said hot gas line, and automatic means for periodically closing said first valve and opening said second valve and for opening said first valve and closing said second valve.

10. Apparatus of the character described comprising, a compressor, a condenser, a refrigeration chamber, an evaporator located within said chamber and having an inlet and an outlet, the inlet of said evaporator being in operative connection through the condenser with the discharge of the compressor, a hot gas line connecting the outlet of the compressor with the inlet 01 said evaporator without passing through the condenser, an evaporating coil located without said chamber and having an inlet and an outlet, a fluid conducting conduit connecting the outlet of the evaporator that is within the chamber with the inlet of the evaporating coil that is without the chamber, a fluid conducting conduit connecting the outlet of the evaporating coil that is without the chamber with the inlet of the compressor, and pressure reducing means in the said conduit which connects the outlet of the evaporator that is within the chamber with the inlet of the coil that is without the chamber, the parts being so constructed and arranged that the surrounding air may be circulated in contact with the outer surface of the coil that is located without the chamber to augment its effect upon the fiuid passing therethrcugh.

11. Apparatus of the character described comprising, a compressor, a condenser, a refrigeration chamber, an evaporator located within said chamber and having an inlet and an outlet, the inlet of said evaporator being in operative connection through the condenser with the discharge of the compressor, a hot gas line connecting the outlet of the compressor with the inlet 01' said evaporator without passing through the com denser, an evaporating coil located without said chamber and having an inlet and an outlet, 8. fluid conducting conduit connecting the outlet of the evaporator that is within the chamber with the inlet of the evaporating coil that is without the chamber, a fluid conducting conduit connecting the outlet of the evaporating coil that is without the chamber with the inlet of the compressor, pressure reducing means in the said conduit which connects the outlet of the evaporator that is within the chamber with the inlet of the coil that is without the chamber, and air circulating means associated with the evaporating coil that is without the chamber to augment its effect upon the fluid passing therethrough.

12. Apparatus of the character described comprising, a compressor, a condenser, a refrigeration chamber, an evaporator located within said chamber and having an inlet and an outlet, the inlet of said evaporator being in operative connection through the condenser with the discharge of the compressor, a hot gas line connecting the outlet of the compressor with the inlet of said evaporator without passing through the condenser, a second evaporator located without said chamber and having an inlet and an outlet, a fluid conducting conduit connecting the outlet of the evaporator that is within the chamber with the inlet of the said second evaporator, a fluid conducting conduit connecting the outlet of the said second evaporator withthe inlet of the compressor, pressure reducing means in the said conduit which connects the outlet of the evaporator that is within the chamber with the inlet of said second evaporator, and automatic means for opening and closing said hot gas line.

13. Apparatus of the character described comprising, a compressor, a condenser, a refrigeration chamber, an evaporator located within said chamber and having an inlet and an outlet, the inlet of said evaporator being in operative connection through the condenser with the discharge of the compressor, a hot gas line connecting the outlet of the compressor with the inlet of said evaporator without passing through the condenser, a second unenclosed evaporator located without said chamber so as to be surrounded by circumambient atmosphere and having an inlet and an outlet, a fluid conducting conduit connecting the outlet of the evaporator that is within the chamber with the inlet of said second evaporator, a fluid conducting conduit-connecting the outlet of the said second evaporator with the inlet of the compressor, pressure reducing means in the said conduit which connects the outlet of the evaporator that is within the chamber with the inlet of said second evaporator, and automatic means for opening and closing said hot as line.

O'I'IO J. NUSSBAUM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,384,210 Sunday Sept. 4, 1945 2,440,146 Kramer Apr. 20, 1948 2,440,534 Atchison Apr. 27, 1948 2,455,421 Kirkpatrick Dec. 7, 1948 2,487,182 Richard Nov. 8, 1949 FOREIGN PATENTS Number Country Date 59,500 Switzerland Jam-20, 1912 

